fix: ignore extraneous Erlang output during when CLI installation

[lucaspin]

Issue

As part of supporting Ubuntu 22 ARM in agent-aws-stack, we reached an issue with the when CLI installation. For some reason, the erl command used to determine the version of Erlang/OTP returns some junk and not only the version we are interested in:

Erlang version: =ERROR REPORT==== 30-Apr-2025::21:44:30.114827 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: .. Function: read_file_info. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.115317 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./maps.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.119437 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./logger_formatter.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.123005 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./standard_error.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.124423 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./string.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.132585 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./supervisor_bridge.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.134116 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./unicode_util.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.219142 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./io_lib.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.221839 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./inet_db.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.252741 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./io_lib_format.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.255448 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./inet_config.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.258994 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./epp.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.263716 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./inet_udp.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.267596 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./io_lib_pretty.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.271321 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./inet.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.305718 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./erl_scan.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.309813 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./inet_parse.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.316695 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./inet_gethost_native.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.323713 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./rpc.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.326941 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./global.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.332291 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./net_kernel.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.341387 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./rand.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.346562 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./erl_distribution.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.348264 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./global_group.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.353477 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./erpc.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.357317 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./user_sup.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.359145 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./user_drv.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.363462 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./gen_statem.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.369089 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./prim_tty.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.382769 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./io.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.388798 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./group.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.395718 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./edlin.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.398882 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./logger_sup.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.401521 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./edlin_key.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.402824 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./logger_handler_watcher.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.404594 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./kernel_config.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.406334 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./kernel_refc.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.408109 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./erl_signal_handler.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.409589 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./logger_std_h.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.412476 ===
    label: {erl_prim_loader,file_error}
    report: File operation error: eacces. Target: ./logger_h_common.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.114827 ===
File operation error: eacces. Target: .. Function: read_file_info. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.115317 ===
File operation error: eacces. Target: ./maps.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.119437 ===
File operation error: eacces. Target: ./logger_formatter.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.123005 ===
File operation error: eacces. Target: ./standard_error.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.124423 ===
File operation error: eacces. Target: ./string.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.132585 ===
File operation error: eacces. Target: ./supervisor_bridge.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.134116 ===
File operation error: eacces. Target: ./unicode_util.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.219142 ===
File operation error: eacces. Target: ./io_lib.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.221839 ===
File operation error: eacces. Target: ./inet_db.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.252741 ===
File operation error: eacces. Target: ./io_lib_format.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.415915 ===
File operation error: eacces. Target: ./c.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.420388 ===
File operation error: eacces. Target: ./orddict.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.422703 ===
File operation error: eacces. Target: ./raw_file_io.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.424144 ===
File operation error: eacces. Target: ./erl_anno.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.426196 ===
File operation error: eacces. Target: ./ordsets.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.427552 ===
File operation error: eacces. Target: ./otp_internal.beam. Function: get_file. Process: code_server.
=ERROR REPORT==== 30-Apr-2025::21:44:30.429389 ===
File operation error: eacces. Target: ./erl_internal.beam. Function: get_file. Process: code_server.
26

Due to that, the ERLANG_VERSION variable ends up having some spaces in it, so the mv command here ends up being expanded to a move command that tries to move multiple files. Since moving multiple files, the mv command expects the last argument to be a directory, the when CLI fails to be installed with the cannot access '/usr/local/bin/when': No such file or directory error message.

Weirdly enough, that only happens when the install script runs as part of an Ansible task, and not in all cases - for example, if the install-toolbox toolbox script is run separately from the install.sh agent installation script, it works just fine. Also, if I run that command through any other means, I don't see those errors.

Ref: https://github.com/renderedtext/tasks/issues/7932

Solution

I couldn't find a reasonable explanation of why Erlang shows these errors inconsistently (only during Ansible task when the script runs as part of another script invocation), so I think the best route forward here is to update the install-toolbox script to just ignore that extra output.